Vacuum pump

ABSTRACT

A vacuum pump, particularly a rotary vane pump with a high pumping capacity, has a pump chamber in a housing. A pump element is arranged in the pump chamber. The pump element is supported by a rotor shaft. The rotor shaft is connected to a belt pulley arranged outside of the pump housing. The pump also has a motor arranged outside of the pump housing. The drive shaft of the motor carries a drive pulley. The drive pulley is connected to the rotor pulley via a belt. To simplify assembly, the drive pulley and/or the rotor pulley are formed of multiple parts.

BACKGROUND

1. Field of the Disclosure

The disclosure relates to a vacuum pump.

2. Discussion of the Background Art

Large vacuum pumps are driven by an external motor that is not arranged in the pump housing. Large vacuum pumps are, in particular, rotary vane pumps with a suction capacity of more than 200 m³/h. Likewise, the pumps may be screw-type pumps or Roots pumps which, due to their size, are also driven by an external motor. Such pumps comprise a pump housing defining a pump chamber. In the pump chamber, a pumping element, such as a rotor, is arranged and connected with a rotor shaft. With a rotary vane pump, the pumping element is a rotor arranged eccentrically in the pump chamber and comprising displaceable vanes arranged in slots formed in the rotor. Outside of the pump housing, a belt pulley is connected with the rotor shaft. Further, the vacuum pump has a motor arranged outside the pump housing, a drive pulley being arranged on the drive shaft of the motor. The drive pulley is connected with the belt pulley via a belt. Since the belt becomes stretched in operation, a tensioning element is further provided for tensioning the belt. The tensioning element is also required for mounting the belt pulley and the drive pulley, respectively. If, for example, the belt pulley is already mounted and the belt is placed on the belt pulley, the drive pulley can only be mounted if the belt is loose. Owing to this assembly requirement, it is not possible to use constant-length belts, i.e. belts that do not become longer in operation.

It is an object of the disclosure to provide a vacuum pump with a high pumping capacity, which also allows for the use of a constant-length belt.

SUMMARY

A vacuum pump which, according to the disclosure, is a vacuum pump with a high pumping capacity, i.e. a suction capacity of more than 200 m³/h, comprises a pump housing defining a pump chamber. In the pump chamber, a pumping element is arranged and connected with a rotor shaft. For example, the pumping element may be a rotor of a rotary vane pump, which arranged eccentrically in the pump chamber and carries vanes. Likewise, the pumping element may be a rotor of a screw-type pump. The rotor shaft is driven by an external motor arranged outside the pump housing. For this purpose, a drive pulley is connected with the drive shaft of the motor and a belt pulley is connected with the rotor shaft, the belt pulley being arranged outside the pump housing. A belt is provided for power transmission, the belt being connected with the drive pulley and the belt pulley. According to the disclosure, the drive pulley or the belt pulley is of a multipart structure. Thereby, when mounting the belt, it is possible to first mount only a part of the drive pulley or of the rotor pulley or, respectively, not to mount a part of the drive pulley or the rotor pulley. Thereafter, the belt can be placed in a simple manner, since, due to the multipart nature of the drive pulley and/or the belt pulley, the pulley not yet fully mounted can be adjusted such that the belt is not yet tensioned. If the drive pulley is comprised of two parts, for example, of which one part corresponds to 100° and the other part corresponds to 260° of the drive pulley, for example, it is possible not to mount the smaller of the two parts, for example, and to adjust the drive pulley such that the belt extends along a section of the mounted part of the drive pulley. Thereafter, the drive pulley is turned until the belt fully engages the outer circumference of the part of the drive pulley already mounted, and is tensioned thereby. In the next step, the second part of the drive pulley can then be mounted.

If, for instance, the two pulleys are provided side by side or on the same level, and the drive pulley is arranged on the left side, the first part of the drive pulley, e.g. the part forming 260° of the circumference, is mounted such that the outer surface of this part of the drive pulley, which in operation is in contact with the belt, is directed downwards. When the belt has been mounted subsequently, the same extends freely above the already mounted part of the drive pulley and thus is slightly sagging. Then, the drive pulley is turned clockwise until the already mounted part of the drive pulley is located on the outer left side with respect to the arrangement described. Thereby, the belt is tensioned. The second part of the drive pulley can thus be mounted, within the belt, on the right side of the already mounted part of the drive pulley or on the side between the drive pulley and the belt pulley.

The provision of a multipart drive pulley and/or a multipart belt pulley, as provided by the disclosure, has the advantage that constant-length belts can be used. These are belts that, in operation, do not become substantially longer. This has the essential advantage that no tensioning device must be provided. With known vacuum pumps having a belt drive, the tensioning device functions to keep the belt taut and to allow for a loosening of the belt for mounting purposes.

It is another advantage of the multipart drive pulley of the present disclosure and/or the multipart belt pulley of the present disclosure that, independent of the power supply network which has 50 Hz or 60 Hz, for example, the same motor can be used for the pump. This is possible due to the fact that a constant pump speed is achieved by correspondingly adapting the diameter of the drive pulley or the belt pulley. This may well be possible also with known pumps; however, a changeover, for example, is extremely complex. With vacuum pumps according to the disclosure, a changeover merely requires a replacement of the divided pulley and the provision of a belt of corresponding length. This is advantageous, in particular during manufacture, in that it has to be decided only just before the final assembly, whether the pump is used with a power supply network of 50 Hz or 60 Hz. If both the drive pulley and the belt pulley are changed, the diameters can be matched such that it is possible to always use the same belts.

In a particularly preferred embodiment the drive pulley and/or the belt pulley are of a two-part structure. This has the advantage that the assembly is simplified when compared to single-part or multipart pulleys.

Preferably, the divided pulley comprises a holding part that includes a shaft receiving means. The connection between the divided pulley and the corresponding shaft is thus effected in particular exclusively via this shaft receiving means. Accordingly, the connection between the pulley and the shaft is realized by means of the holding part. The part or the further parts of the corresponding pulley are then merely connected with the holding part and no longer serve to fix the pulley on the shaft. This facilitates the assembly further, since a secure connection with the shaft is already made after the holding part is mounted on the shaft.

Further, in another preferred embodiment, the divided pulley, i.e. the drive pulley or the rotor pulley, comprises a connecting part with a circular segment-shaped cross section. This connecting part is connected in particular with the holding part so that, in a particularly preferred embodiment, a two-part pulley is formed that comprises a holding part and a connecting part.

A connecting part which preferably has a circular segment-shaped cross section, but which may have a different cross section, and the holding part, which preferably comprises the shaft receiving means, each comprise a connecting element for their connection with one another. The two connecting elements form a connecting web. The same extends preferably corresponding to a secant of a circle. Thus, the connecting web is preferably provided outside the shaft receiving means and does not extend through the center. For the purpose of achieving an assembly that is as simple as possible, the two connecting elements extend in parallel with each other. Preferably, the connection of the two connecting elements is effected by means of fixing elements such as screws or the like. The belt is preferably designed as a flat belt and is length-constant in operation.

Preferably, when seen in cross section, the belts have a plurality of beads and grooves extending in parallel with each other and cooperating with corresponding beads and grooves in the peripheral surfaces of the belt pulley and the drive pulley.

In a particularly preferred embodiment, the vacuum pump of the present disclosure is a rotary vane pump with high pump capacity, especially a single-stage rotary vane pump with a suction capacity of more than 200 m³/h.

The disclosure will be described in more detail hereunder with reference to a preferred embodiment and the accompanying drawings.

In the Figures:

FIG. 1 is a schematic top plan view of a vacuum pump with belt drive,

FIG. 2 is a schematic top plan view of a divided drive pulley, and

FIGS. 3 and 4 are schematic front views of the belt drive in different assembly positions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

A vacuum pump, such as a rotary vane pump, has a pump housing 10. A pump chamber 12, illustrated in a schematic, much simplified manner in FIG. 1, is defined in the pump housing 10. In the pump chamber 12, a pumping element 14 is arranged which takes the form of a rotor. The rotor 14, which is arranged eccentrically with respect to the center line of the pump chamber, carries radially displaceable vanes 16. Due to the vanes 16 being displaceable in the radial direction, a plurality of chambers are formed whose volume decreases because of the rotation of the pumping element 14. Thereby, gas is drawn through an inlet 18 into a large pump chamber, the gas then being compressed and expelled through an outlet 20.

The pumping element is supported by a rotor shaft 22 and is driven by this rotor shaft 22. The rotor shaft 22 extends outward from the pump housing 10 and carries a belt pulley 24.

Further, a motor 26 is provided that is arranged outside the housing 10, the drive shaft 28 of the motor carrying a drive pulley 30. The rotary movement is transmitted from the drive pulley 30 to the belt pulley 24 by means of a belt 32.

According to the disclosure, the drive pulley 30 and/or the belt pulley 24 are of a multipart structure. FIG. 2 shows a two-part pulley which, for example, is a drive pulley 30. The drive pulley 30 is of a two-part design and is composed of a holding part 34 and a connecting part 36 with a circular segment-shaped cross section, seen in top plan view.

It is a particularly preferred aspect of the disclosure that the connection between the holding part and the corresponding associated shaft 22 or 28 is realized via a shaft receiving means 38 that is fully integrated in the holding part. The connection between the pulley, i.e. the drive pulley 30 in the embodiment illustrated, and the corresponding shaft is realized exclusively through the shaft receiving means 38 integrated in the holding part 34. The shaft receiving means 38 is connected with a partial circumference ring 42 through substantially radially extending webs 40. Further, the holding part 34 comprises a connecting element 44 in the form of a secant of a circle. The same is arranged such that it is located outside the shaft receiving means 34. In other words: the shaft receiving means 34 is arranged inside the partial ring 42 as well as inside the connecting element 44.

In top plan view, the connecting part 36 has a circular segment-shaped cross section. The connecting part 42 also comprises a partial circumference ring 46. The same is connected with a connecting element 48. Corresponding to the connecting element 44, the connecting element 48 is designed as a secant of a circle. The two connecting elements 44, 48 form a connecting web. Since, in the embodiment illustrated, the connecting elements 44, 48 are formed in parallel with each other, they can be connected with each other in a simple manner using bores 50 and 52, possibly with threads, and fixing elements, such as screws, not illustrated herein.

Referring to FIGS. 3 and 4, a description will be made hereunder of the assembly according to the disclosure, which no longer requires the provision of a tensioning device due to the multipart design of the drive pulley 30 and/or the belt pulley 24.

For assembly, for example, a single-part belt pulley 24 can be mounted on the rotor shaft 22 in a first step (FIG. 3). In the next step the holding part 34 of the drive pulley 30 is mounted on the drive shaft 28. Thereafter, the belt 32 can be installed. Due to the arrangement of the holding part 34, the belt sags and can be placed in a simple manner. Possibly existing beads extending in the longitudinal direction of the belt 32 and corresponding recesses in the pulleys 24, 30 do not interfere with the assembly.

In the next step the holding part 34 is turned to the position illustrated in FIG. 4. In doing so, the belt 32 is automatically tensioned. No tensioning device is required for this purpose. Thereafter, the connecting part 36 can be mounted in a simple manner from inside, i.e. in a position inside the belt 32, so that the drive pulley 30 is mounted.

By means of corresponding assembly steps and changing one or both pulleys 30, 34, an adaptation to different power supply networks can be made, for example. 

What is claimed is:
 1. A vacuum pump with a high pumping capacity, comprising a pump housing defining a pump chamber, a pumping element connected with a rotor shaft, a belt pulley connected with the rotor shaft outside the pump housing, and a motor arranged outside the pump housing, the drive shaft thereof being provided with a drive pulley that is connected with the belt pulley via a belt, wherein the drive pulley and/or the belt pulley are of a multipart structure.
 2. The vacuum pump of claim 1, wherein the drive pulley and/or the belt pulley are of a two-part design.
 3. The vacuum pump of claim 1, wherein the holding part of the drive pulley and/or the belt pulley comprise a shaft receiving means.
 4. The vacuum pump of claim 3, wherein the drive pulley and/or the belt pulley is connected with the drive shaft or the rotor shaft exclusively via the shaft receiving means of the holding part.
 5. The vacuum pump of claim 1, wherein the drive pulley and/or the belt pulley comprise a connecting part with a circular segment-shaped cross section.
 6. The vacuum pump of claim 1, wherein, for connection with each other, a connecting part and a holding part each comprise a connecting element which form a connecting web.
 7. The vacuum pump of claim 6, wherein the connecting web extends outside the shaft receiving means and is formed in particular in a manner corresponding to a secant of a circle.
 8. The vacuum pump of claim 6, wherein the connecting elements extend in parallel with each other and are preferably connected with each other by means of fixing elements.
 9. The vacuum pump of claim 1, wherein the belt is in the form of a flat belt.
 10. The vacuum pump of claim 1, wherein the belt is length-constant in operation. 